1. Field of the Invention
The present invention relates to a novel apparatus and method for treating liquids containing dissolved and/or entrained gas to eliminate bubbles therefrom and to prevent bubbles from forming subsequently. More particularly the invention relates to acoustically debubbling a solution, or a dispersion such as gelatin-silver halide photographic emulsion, to eliminate bubbles therefrom and to prevent the subsequent formation of bubbles therein.
2. The Prior Art
The treatment of liquids ultrasonically for the purpose of removing or avoiding gas bubbles has been proposed in the past in such patents as U.S. Pat. Nos. 3,463,321 and 3,461,651 for photographic gelatin-silver halide emulsions, and U.S. Pat. No. 2,620,894 for viscose. While these previous proposals have been successful, they are not as efficient or as thorough as is desirable for removing detrimental gas bubbles from a photographic emulsion or other liquid.
Certain of the prior art techniques have involved causing entrained air to dissolve into the liquid by a combination of high pressure and ultrasonic energy. Such a solution tends to become saturated, or even super saturated, with gas so that a reduction in pressure at the coating station may cause some of the dissolved gas to come out of solution and thus form bubbles, lines and streaks during coating of the film or paper. Another technique has involved expelling gas bubbles from the liquid. A combination of the two has been used also.